Dozens of Australian Federal Police officers will begin patrols in Papua New Guinea today despite concerns from some officers that they will be unarmed, unprotected and unable to properly carry out their jobs.

Code-named Operation Copperplate, 50 AFP officers will be working in an advisory role to the existing PNG police force.

But the AFP Association says some of its members fear the high visibility roles, combined with a lack of powers, will make them an easy target.

A similar deployment was withdrawn in 2005 when a constitutional challenge eroded any immunity Australian officers had against prosecution in the country.

So this time the AFP says its officers will only be there to watch and offer advice.

The AFP Association has opposed any further policing involvement until PNG grants immunity to Australian police and changes its stance on the death penalty.

AFP Association chief executive officer Dennis Gellatly says his members are worried they are being placed at unnecessary risk.

"That sort of thing in our view would be a very outside chance - that our members might be subject to some sort of prosecution where the death penalty might be a result," he said.

"But it's more so about the operational nature of the deployment and the nature of the duties and the tools with which, or in this case, we don't, have."